The present invention relates to fiber-reinforced rubber hoses used for, for example, automotive radiator and automotive tubing for cooling down the automatic transmission fluid.
Hitherto, there have been proposed various fiber-reinforced rubber hoses. For example, Japanese Utility Model Examined Publication JP-Y-6-47720 discloses a fiber-reinforced rubber hose having an inner tubular rubber portion, an outer tubular rubber portion, and a reinforcing layer interposed therebetween. It is disclosed in this publication that at least one of the inner and outer rubber portions is prepared by using a special rubber composition. This rubber composition is a blend of 70-90 wt % of a carboxyl-containing acrylic copolytmerized elastomer and 30-10 wt % of a carboxyl-containing ethylene-acrylate copolymer elastomer. The reinforcing layer of this rubber hose is made of aromatic polyamide fibers. In general, aromatic polyamide fibers are superior in heat resistance, chemical resistance and strength, but are very high in price. Thus, the use of aromatic polyamide fibers may substantially increase the production cost of fiber-reinforced rubber hoses. Such conventional fiber-reinforced rubber hoses are superior in heat resistance, oil resistance, pressure resistance, and sealing capability to prevent leak from a joint where a metal pipe has been pressed into the rubber hose. Recently, some metal pipes have been plated with Sn and Zn for the anticorrosive purpose. It is thus desired to provide a fiber-reinforced rubber hose which hardly deteriorates even if it is in contact with such a Sn--Zn plated metal pipe. In general, a snow melting agent (calcium chloride) is scattered on the road in the winter in a snowy region. In case that a fiber-reinforced rubber hose is attached to the bottom of a vehicle, the outer surface of the hose may be contaminated with calcium chloride. It is thus desired to provide a fiber-reinforced rubber hose which hardly deteriorates even if its outer surface is contaminated with calcium chloride.
Japanese Patent Unexamined Publication JP-A-6-99515 does not disclose a fiber-reinforced rubber hose, but an oil-resistant hose. This oil-resistant hose is made of a steam vulcanizate of a first carboxyl-containing acrylic elastomer prepared by copolymerizing a monualkyl maleate, which is used as a carboxyl-containing monomer, with at least one other monomer. This publication further discloses another oil-resistant hose made of a steam vulcanizate of a blend of the first carboxyl-containing acrylic elastomer and a second carboxyl-containing acrylic elastomer prepared by copolymerizing a monoalkyl maleate, ethylene and at least one other monomer. It is disclosed in this publication that polyamine is used as a preferable vulcanizing agent for preparing the oil-resistant hose.